The present invention relates to a semiconductor device, a semiconductor package and a semiconductor module wherein radiation of undesired electromagnetic waves is controlled.
With the development of multimedia, there are increasing demands for high-speed data processing and high-speed data transmission. To meet these demands, research and development is actively being carried out into both hardware and software, and there have been noticeable improvements in performance.
In particular, in the field of semiconductor technology, there has been progress in increasing the speed and performance of a microprocessor, the nucleus of a computer, and increasing memory speed and capacity, and high-speed data processing and data transmission is now possible even with an inexpensive personal computer.
However, as a result of increased high-speed and high performance of LSI, undesired electromagnetic waves radiated from electronic equipment have become stronger, increasing together with frequencies, and it is feared that these may have an adverse influence not only on other electronic equipment but also on human beings.
Most radiation of undesired electromagnetic waves is caused by noise occurring between signal wires and the power layer and ground layer due to signal reflection and crosstalk between wires, switching of semiconductor elements and the like, in a circuit board comprising electronic components such as LSI or passive components mounted on a wiring board. This noise causes undesired electromagnetic waves to be radiated from the circuit board, as well as outside the device through heat-dissipation holes or the like in the case.
This radiation of undesired electromagnetic waves divides into waves radiated from the surface of a substrate when a high-speed signal, such as a clock signal, propagates through a circuit pattern formed on the substrate, and waves radiated from the sides of the substrate as a result of resonance between the power layer and the ground layer.
As described in xe2x80x9cMethods for Reducing Unwanted Emission Originating in the Power Layer and Ground Layer of a Printed Wiring Boardxe2x80x9d in the collection of lectures and papers of the 11th Circuit Mounting Technology Lecture Meeting, wave radiation caused by resonance between the power layer and the ground layer can be controlled by providing insulating layers on each side of the power layer to insulate the power layer from the ground layer.
On the other hand, as for instance described in Jpn. Pat. Appln. KOKAI Publication No. 8-228055, wave radiation from the surface of a substrate on which a circuit pattern is formed can be controlled by a shield method wherein a copper paste is applied to the surface of the circuit pattern, with a solder resist in between, and this copper paste is connected to ground.
Furthermore, as disclosed in Jpn. Pat. Appln. KOKAI Publication No. 9-18099, there is another known method wherein, signal wires are provided symmetrically on both sides of a ground wire, so that electromagnetic waves arising from the signal wires cancel each other out, thereby preventing the generation of the undesired electromagnetic waves themselves.
However, with regard to reliability and performance, the above methods have had the following problems. The shield method using copper paste proposed in Jpn. Pat. Appln. KOKAI Publication No. 8-228055 has reliability problems, since weak contact between the copper paste and the solder resist can cause peeling.
On the other hand, the method of symmetrically providing signal wires on both sides of a ground wire so that electromagnetic waves arising from the signal wires cancel each other out, proposed in Jpn. Pat. Appln. KOKAI Publication No. 9-18099, has performance problems since the reduction effect of radiated electromagnetic waves is less than 10%.
In addition, undesired electromagnetic waves are radiated from electronic components, such as a connector, mounted on a printed board. This is mainly a result of the fact that the wires on the printed board and the pin structure inside the connector, provided roughly at a right angle to the printed board, constitute an antenna.
Proposed countermeasures include, as disclosed in Jpn. Pat. Appln. KOKAI Publication No. 9-199235, controlling noise radiation by inserting a ring-shaped core into the connector, or, as disclosed in Jpn. Pat. Appln. KOKAI Publication No. 9-82420, providing a conductive cover over the outer wall of the connector before connecting it to ground, thereby shielding the pin inside the connector and controlling leakage and radiation of electromagnetic waves.
However, these various conventional techniques require a special connector structure and consequently increase the cost of the connector. Since a great number of connectors are used in a semiconductor device, an increase in the cost of connectors leads to a considerable increase in the cost of the semiconductor device.
Furthermore, another cause of radiation of undesired electromagnetic waves from a printed wiring board is a through-hole portion (wherein a signal transmission path is provided within a through-hole). That is, a through-hole portion, and a wiring pattern on the board surface which is connected to the through-hole portion, together produce a structure which has the same configuration as a microstrip antenna, and consequently electromagnetic waves radiate from the through-hole portion.
However, in conventional technology, it has been difficult to control radiation of undesired electromagnetic waves from a through-hole portion.
As regards undesired electromagnetic waves radiating from the mount structure of a semiconductor component, the problem of radiation from the pin portion is revealed in, for instance, B-4-17 in the collection of lectures and papers of the 1997 Lecture Meeting of the Electronic Data Communication Academy Communications Society.
However, as pointed out in edition 114 (pp.72 to 77) of the Environmental Electromagnetic Engineering Special Magazine EMC, a present-day semiconductor package structure does not control radiation of electromagnetic waves, and since there have been no specific suggestions for improvement or patent applications, this problem remains to be solved.
But, undesired electromagnetic waves are radiated from a semiconductor package because wires provided on a wiring board and leads of the semiconductor package together form a structure which acts as an antenna.
Here, it is technically possible to reduce radiation of undesired electromagnetic waves by changing the shape of the leads, but since specifications of semiconductor components, including lead shapes, are defined by world standards, it is extremely difficult and time-consuming to change the shape of leads.
However, due to increasing world-wide restrictions on the environmental problem of unwanted electromagnetic wave radiation, there is a demand in present standard specifications for a method of controlling radiation of electromagnetic waves.
Accordingly, a first object of the present invention is to provide a semiconductor device capable of reducing radiation of undesired electromagnetic waves without loss of reliability.
A second object of the present invention is to provide a semiconductor device wherein radiation of undesired electromagnetic waves from a connector can be controlled without increasing the cost of the connector.
A third object of the present invention is to provide a semiconductor device wherein radiation of electromagnetic waves from a through-hole portion can be controlled.
A fourth object of the present invention is to provide a semiconductor package wherein radiation of undesired electromagnetic waves can be controlled and a semiconductor device using the same.
A fifth object of the present invention is to provide a semiconductor module wherein radiation of undesired electromagnetic waves can be controlled.
In order to achieve the above first object, the semiconductor device of the present invention comprises a first signal wire provided on a substrate; a pair of second signal wires provided along both sides of the first signal wire on the substrate; an inverse signal of an input signal, which is input to the first signal wire, is input to the second signal wires, and in addition, when the amplitude of the input signal is V1 and the amplitude of the inverse signal is V2, the relation 0.3 V1xe2x89xa6V2xe2x89xa60.8 V1 is satisfied.
According to research conducted by the present inventor, by providing second signal wires on both sides of the first signal wire and inputting to the second signal wires an inverse signal of the signal inputting to the first signal wire, while also setting the voltage amplitude of the inverse signal to more than 0.3 and less than 0.8 of the voltage amplitude of the input signal, it is possible to adequately control radiation of undesired electromagnetic waves.
Furthermore, according to such a technique for controlling radiation of undesired electromagnetic waves, basically it is only necessary to add a wire for inverse signal and a signal source, and a copper paste is not required, and therefore, unlike the conventional shield method disclosed in Jpn. Pat. Appln. KOKAI Publication No. 8-228055, there is no disadvantage such as loss of reliability due to peeling of copper paste and solder resist.
Therefore, according to the present invention, it is possible to realize a semiconductor device wherein radiation of undesired electromagnetic waves can be controlled, without loss of reliability.
Furthermore, in order to achieve the second object, the semiconductor device of the present invention comprises a signal wire provided on a substrate; a connector having a first connector terminal, provided on the substrate and connected to the signal wire, and at least one second connector terminal, provided next to the first connector terminal; an inverse signal of an input signal, which is input to the first connector terminal, being input to the second connector terminal.
According to such a constitution, an inverse signal, being the inverse of the signal input to the first connector terminal, is input to the second connector terminal, whereby undesired electromagnetic waves radiated from the first and second connector terminals cancel each other out, and consequently undesired electromagnetic waves radiated from the connector can be controlled.
Furthermore, since this technique of controlling radiation of undesired electromagnetic waves can basically be performed by adding a connector terminal and an inverse signal source, it does not require a special connector structure, and consequently increased connector cost can be controlled.
Therefore, according to the present embodiment, radiation of undesired electromagnetic waves from the connector can be controlled without increasing the cost of the connector.
Furthermore, in order to achieve the third object, the semiconductor device of the present invention comprises a first through hole portion, provided in a substrate; at least one second through hole portion, provided in the substrate next to the first through hole portion; an inverse signal of an input signal, which is input to the first through hole portion, being input to the second through hole portion.
According to such a constitution, an inverse signal of the input signal applied to the second through hole portion is input to the first through hole portion, so that undesired electromagnetic waves radiating from the first and second through hole portions cancel each other out, thereby enabling undesired electromagnetic waves radiated from the through hole portions to be controlled. Therefore, according to the present embodiment, a semiconductor device capable of controlling radiation of undesired electromagnetic waves from through hole portions can be realized.
Furthermore, in order to achieve the fourth object, the present invention comprises a semiconductor package for mounting a semiconductor chip, comprising a first signal input portion, which a first signal is input to; and at least one second signal input portion, which an inverse signal of the first signal is input to, provided next to the first signal input portion.
Furthermore, in order to achieve the fourth object, the semiconductor device of the present invention comprises a semiconductor package, provided on a wiring board, and comprising a first signal input portion, which a first signal is input to, and at least one second signal input portion, which an inverse signal of the first signal is input to, provided next to the first signal input portion; and a semiconductor chip, mounted on the semiconductor package.
According to such a constitution, an inverse signal of the signal input to the first signal input portion is input to the second signal input portion, whereby undesired electromagnetic waves radiated from the first and second signal input portions cancel each other out, consequently enabling undesired electromagnetic waves radiating from the signal input portions to be controlled.
Therefore, it is possible to realize a semiconductor package wherein radiation of undesired electromagnetic waves from a signal input portion can be controlled, and a semiconductor device using the semiconductor package.
Furthermore, this technique of controlling radiation of undesired electromagnetic waves can basically be performed merely by adding a signal input portion and a signal source, and there is no need to alter the shape of the signal input portion. Consequently, according to the present invention, radiation of undesired electromagnetic waves can be controlled, even when the signal input portion is determined by world standards, such as, for instance, specification of the leads in the semiconductor package.
Furthermore, in order to achieve the fifth object, a semiconductor module of the present invention comprises a first signal wire provided on a substrate; a pair of second signal wires provided along both sides of the first signal wire on the substrate; an inverse signal of an input signal, which is input to the first signal wire, is input to the second signal wires, and in addition, when the amplitude of the input signal is V1 and the amplitude of the inverse signal is V2, the relation 0.3 V1xe2x89xa6V2xe2x89xa60.8 V1 is satisfied; a third signal wire, provided on the substrate; and a connector having a first connector terminal, provided on the substrate and connected to the third signal wire, and at least one second connector terminal, provided next to the first connector terminal, an inverse signal of an input signal, which is input to the first connector terminal, being input to the second connector terminal; a first through hole portion, provided in the substrate; at least one second through hole portion, provided in the substrate next to the first through hole portion; an inverse signal of an input signal, which is input to the first through hole portion, being input to the second through hole portion; and a semiconductor package provided on the substrate, comprising a first signal input portion, which a first signal is input to, and at least one second signal input portion, which an inverse signal of the first signal is input to, provided next to the first signal input portion; and a semiconductor chip, mounted on the semiconductor package.
According to such a constitution, undesired electromagnetic waves radiating from the signal wire, the connectors, the through hole portions and the semiconductor package, which are main sources of undesired electromagnetic waves, can be controlled, and therefore, radiation of undesired electromagnetic waves from the semiconductor module can be effectively and adequately reduced.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.